1. Field of the Invention
The present invention relates to a multi-touch positioning method, and more particularly, to a multi-touch positioning method for a touch control device.
2. Description of the Prior Art
A touch control display device has been widely utilized among electrical products. The touch control display device is composed by a display panel and a transparent touch panel. Through attachment of the display panel to the transparent touch panel, the touch control display device can realize functions of touch control as well as display. Nowadays, capacitive touch control is the most popular technique.
Please refer to FIG. 1, which illustrates a schematic diagram of a conventional capacitive touch control display device 10. As shown in FIG. 1, the capacitive touch control display device 10 includes a touch control sensing glass 100 and a flexible circuit board (not shown in figure), and the touch control sensing glass 100 is interlaced by Indium Tin Oxide (ITO) to form a sensing array at its surface. Further, when a human being (object) touches the touch control display device, the human being and the sensing array form a coupling capacitor, where the sensing array is interlaced by vertical-axis (X-axis) sensing lines LA1-LAm and horizontal-axis (Y-axis) sensing lines LB1-LBn to sense capacitance changes of the coupling capacitor, so as to calculate a coordinate of a touch point. In order to simultaneously retrieve the capacitance changes of the coupling capacitor both at the vertical axis as well as the horizontal axis, the sensing array needs to be stacked with two layers of Indium Tin Oxide to form the vertical-axis sensing lines LA1-LAm and the horizontal-axis sensing lines LB1-LBm and to provide better calculating accuracy of the coordinate of the touch point. However, the above process needs to utilize a plurality of layers of Indium Tin Oxide and costs a lot. During the process of stacking the sensing array, higher accuracy is needed to qualify an applicable range of the capacitive touch control display device 10.
U.S. Pat. No. 4,087,625 discloses another type of capacitive touch control display device. Please refer to FIG. 2A, which illustrates a schematic diagram of a conventional capacitive touch control display device 20. As shown in FIG. 2A, the sensing array 200 is realized by single-layer pair triangles. The structure of the pair triangles provides a solution simplifying the two-layer sensing array into a single-layer sensing array. By utilizing the single-layer sensing array, a complex production process can be simplified, and production costs effectively controlled.
Furthermore, U.S. Patent Publication Number 2010/0309167 A1 discloses another two-dimensional coordinate multi-touch design. Please refer to FIG. 2B, which illustrates a schematic diagram of a conventional capacitive touch control display device 22. In comparison with the capacitive touch control display device 20 in FIG. 2A, the capacitive touch control display device 22 adjusts number of pair triangles to realize the single-layer sensing array structure as shown in FIG. 2B, where three pairs of triangles are provided to form the sensing capacitance array 220, which simplifies the two-dimensional coordinate to a one-dimensional coordinate to realize multi-touch design.
The structure of the single-layer Indium Tin Oxide of the capacitive touch control display device has been simplified to the one-dimensional coordinate multi-touch design. Thus, an important following issue is to provide better sensing accuracy and positioning efficiency, so as to enlarge applicable ranges of different numbers of Indium Tin Oxide sensing arrays.